Dental implants and boring instruments for implanting

ABSTRACT

A surgical equipment for implanting dental implants has a boring instrument and an endo-osseous dental implant. The endo-osseous dental implant has a tubular distal section with a cylindrical wall that turns around an axis, and is provided with an outer thread and delimits an inner bone material holding volume. Its distal end having a thickness &#34;e&#34; which forms a ring-shaped transverse base with an inner diameter &#34;d&#34; and an outer diameter &#34;d+2e&#34;. The cylindrical wall has at least one distal indentation that forms a front cutting edge at the ring-shaped base. Also disclosed is a boring instrument with a stepped drill having a distal section with a diameter between &#34;d&#34; and &#34;d+2e&#34; and a proximal section with a diameter of at least &#34;d+2e&#34; but smaller than the outer diameter of the thread of the dental implant.

The invention relates to surgical equipment for dental implantology andextends to component parts of this equipment, consisting of anendosseous dental implant and of a drilling instrument.

A standard procedure used for the placement of implants in the dentalfield consists mainly of first generating an implant cavity ofdimensions adapted to those of the implant by means of drills ofincreasing diameter, of threading this cavity with a screw thread and ofscrewing said implant in said cavity. In a second phase, after a periodof four to six months called immobilization during which cicatrizationof the bone occurs, a pillar or stump designed to be used as support forthe prosthesis is united with the implant.

Since one of the conditions of success in implantology is the creationof intimate contact between the bone and the implant immediately aftersurgery, one of the difficult phases of this procedure consists ofconstructing an implantology cavity perfectly calibrated to thedimensions of the implant.

Now, in practice, in spite of the use of perfectly calibratedinstrumentation and the meticulousness of the practitioners, it provesdifficult to construct a cavity perfectly adapted to the dimensions ofthe implant and a source of failure in implantology hence results from apoor immediate immobilization of said implant.

In an attempt to remedy this disadvantage, a novel procedure hasconsisted in constructing self-screw threaded implants such as forexample that described in patent EP 237.505 which comprises threelongitudinal cutting edges arranged towards the distal end of saidimplant, each defining an external cavity arranged so as to make itpossible to collect the bone shavings during the placement.

Owing to their self-screw threading character, such implants make itpossible to obtain a better intimate contact with the bone andconsequently to increase the primary stability of said implants.However, in spite of the presence of the external cavities forcollecting the bone shavings, such implants may cause compression of thebone removed which results in a necrosis of the bone cells. Furthermore,the operating procedure for the placement of such an implant proves tobe relatively complex and difficult. In fact, this placement makes itnecessary to carry out in particular a predrilling, a first drillingwith for example a 2 mm drill, another predrilling with the aid of aninstrument comprising a 2 mm diameter blunt tip followed by a 3 mmdiameter sharp-edged part, a second drilling by means of a 3 mm drill,and a widening with the aid of a so-called "counter-sink" special drill.In practice, the operating time required for the surgical placement ofan implant proves to be considerable. In addition, the increase in thenumber of operations to be performed proves to be a not inappreciablesource of potential errors concerning in particular the geometry of thecavity.

The present invention aims to remedy all of the disadvantages previouslymentioned concerning the surgical procedures for the placement of dentalimplants and its essential objective is to provide surgical equipmentwhich, on the one hand, makes it possible to appreciably simplify theoperating procedure for the placement of implants and, on the other, toachieve an intimate bone/implant contact at the time of surgery.

For this purpose, the invention relates to surgical equipment consistingof a drilling instrument and an endosseous dental implant according towhich

the endosseous dental implant consists of:

a proximal section comprising a device for the attachment of a placementtool for said implant, and a threaded upper aperature capable of makingpossible the insertion of a stump,

a distal tubular section comprising a cylindrical wall of rotation aboutan axis defining a internal storage volume of the osseous tissue, andpossessing a distal end of thickness "e" forming an annular transversebase of internal diameter "d" and of external diameter "d+2e", saidcylindrical wall comprising at least one distal indentation forming acutting front edge at the annular base, defined by said annular base andone of the faces of said indentation shaped so as to define a reliefface and a cutting face,

an external threading comprising at least one distal cutting edge,arranged on said dental implant and starting at a distance from theannular base of the distal section,

the drilling instrument comprises a stepped drill having a distalsection of diameter included between "d" and "d+2e" and a proximalsection of diameter at least equal to "d+2e" and less than the externaldiameter of the threading of the dental implant.

For the purpose of inserting an implant such surgical equipment simplymakes it necessary to construct an implant precavity by means of thestepped drill in conformity with the invention, the distal part of whichis adapted to form a bore of smaller diameter than the external diameterof the distal section and the upper section of which is adapted to forma bore of diameter at least equal to this diameter in the very dense andhard cortical part of the bone. It should be noted that this insertionmay, however, first require the carrying out of a predrilling by meansof a standard 2 mm drill, for example.

Once this implant pre-cavity has been formed in one or two operationsonly, the implant can be inserted directly, since it has been designedto generate on insertion a bore in the lower portion of the implantpre-cavity drilled initially by the distal section of the stepped drill,during which the osseous tissue removed by each cutting front edge isstored within the distal section of said implant, on the one hand, and,on the other hand, a self-screw threading.

The operating procedure for the placement of the implants conforming tothe invention thus proves to be very simple and very quick because itonly requires one or two major operations prior to the insertion of theimplants.

Furthermore, from its design, the dental implant according to theinvention, which has a dual bore action with storage of the osseoustissue removed and self-screw threading, makes it possible to obtainboth an optimal intimate contact with the bone and a primary stabilitywithout causing compression of the osseous tissue removed which wouldrisk causing necrosis of the bone cells. As a result it first makes itpossible to diminish the risks of failure of the implantation operation.Furthermore, it causes a rapid osteointegration which allows a reductionof the immobilization time.

According to another characteristic of the invention, the proximalsection of the dental implant comprises a widened upper end portionexhibiting a truncated cone shape, and the stepped drill comprises anupper section, extending the proximal section of truncated cone shapeadapted to that of the dental implant.

This truncated cone shape of the upper section of the drill makes itpossible to create a widening of the end of the implant precavitypossessing a shape identical with that of the upper portion of thedental implant, which advantageously forms an aperture for the alignmentof said implant during its insertion.

Furthermore, once the dental implant has been inserted, such a wideningmakes it possible to obtain an intimate upper portion/bone contact ofsaid implant which is a guarantee against any bacterial penetration.

According to another characteristic of the invention, the cylindricalwall of the distal section of the dental implant has an skewed distalend forming an annular base inclined transversally in the direction ofthe internal volume defined by said peripheral wall.

This skewed form of the annular base comprising the cutting front edgehas the advantage of guiding the bone shavings in the direction of theinternal storage volume of the dental implant.

For the same purpose, the internal storage volume advantageouslypossesses, starting from the annular base, a truncated cone-shapedportion widening in the direction of said annular base.

In addition, in order to enhance the efficacy of the frontal shaving ofthe dental implant the cylindrical wall of the distal sectionadvantageously comprises two indentations arranged symmetrically to oneanother with respect to the longitudinal axis of said dental implant,the annular base possessing between each of the said indentations ahelicoidal shape forming a relief face for each cutting front edge.

According to another characteristic of the invention the cylindricalwall of the distal section comprises at least one longitudinalindentation notch arranged on the external face of said wall, oftransverse section adapted to form a longitudinal cutting edge.

Each of the indentation notches hence possesses a longitudinal cuttingedge for example straight or helicoidal which makes it possible toinitiate the action of self-screw threading of the dental implant. Inaddition, such indentation notches form an external chamber which makesit possible to collect the bone shavings resulting from this self-screwthreading.

Each of these indentation notches may be extended in addition eitherfrom the annular base of the cylindrical wall in an angular positiondisplaced with respect to each indentation, or in the prolongation ofone of said indentations.

Moreover, according to another characteristic of the invention, theexternal threading first possesses, from its distal end, threads oftrapezoidal section extended by threads of triangular cross-section,forming a threading of progressive cross-section.

Furthermore, the threads of this external threading are preferablyspaced so as to define grooves of trapezoidal crosssection.

These external threading forms in fact make it possible, on the onehand, to obtain a progressive self-screw threading and, on the otherhand, to cut away a minimal amount of osseous tissue while guaranteeingperfect retention of the implant in the implant cavity as a result ofthe spacing of the threads.

According to another characteristic of the invention, the cylindricalwall of the distal section comprises circular secondary wedgingapertures the axis of which is non-intersecting with respect to the axisof revolution of said implant.

In addition to their standard function of secondary wedging, suchapertures, owing to their eccentric position with respect to a diametralplane of the implant, possess cutting edges complementary to the passageof the threads of the external threading making it possible to completethe bore of the implant cavity.

Furthermore, the axis of each of these secondary wedging apertures isadvantageously inclined in the direction of the proximal section of saiddental implant, so as to cause the shavings to enter naturally into theinternal storage volume.

Moreover, concerning the device for attachment to the proximal sectionof the dental implant, this latter may advantageously consist in astandard manner of a head of polygonal section.

According to a variant of the embodiment, the upper aperture consists ofa threaded mold of a shape designed to serve also as reserve holeaperture adapted to be attached to a tool for the insertion of saidimplant.

This arrangement which consists of bringing together at the level of aunique portion of the proximal section two zones which are at presentthe prolongation of one another, in fact makes it possible for the samelength of implant to increase the internal storage volume of thislatter.

The invention extends to an endosseous dental implant comprising:

a proximal section comprising a device for attachment to an insertiontool for said implant, and a screw threaded upper aperture capable ofmaking possible the insertion of a stump,

a distal tubular section comprising a cylindrical wall of rotation aboutan axis defining an internal storage volume for the osseous tissue andhaving a distal end of thickness "e" forming an annular transversal baseof internal diameter "d" and external diameter "d+e", said cylindricalwall comprising at least one distal indentation forming a cutting frontedge at the annular base, defined by said annular base and one of thefaces of said indentation shaped so as to define respectively a reliefface and a cutting face,

an external screw threading comprising at least one distal cutting edge,arranged on said dental implant and starting at a distance from theannular base of the distal section.

It also extends to a drill for the generation of an implant cavitydesigned for the insertion of a bone implant, comprising a distalsection of predefined diameter and a proximal section of diametergreater than that of the distal section.

Other characteristics, aims and advantages of the invention will becomeapparent from the detailed description which follows with reference tothe appended drawings which present two preferred embodiments of it asnon-limiting examples. On these drawings which form an integral part ofthe invention:

FIG. 1 is a perspective view of a first embodiment of a dental implantin conformity with the invention,

FIG. 2 is an axial longitudinal section of it,

FIG. 3 is a transverse section of it through a plane A,

FIG. 4 is a longitudinal view in profile of it,

FIG. 5 is a longitudinal section through an axial plane B of a secondembodiment of a dental implant conforming to the invention,

FIG. 6 is a plan view of it

FIG. 7 is a transverse section through a plane C

FIGS. 8 and 9 are two longitudinal views of a stepped drill conformingto the invention at 90° to each other, and

FIGS. 10a to 10d are schematic views representing the different phasesof the insertion of an implant conforming to the invention.

The dental implants presented in the Figures show the feature exhibitingtwo cutting front edges which make it possible to generate a calibratedbore during which the osseous tissue is stored within these implants,and an external threading making it possible to achieve a self-screwthreading.

In the first instance, the dental implant shown in FIGS. 1 to 4 consistsof a distal tubular section 1 comprising a cylindrical wall 2 ofrotation about an axis defining an internal storage volume 3 for theosseous tissue.

This cylindrical wall 2 comprises an internally chamfered distal endsection 2a conferring a flared truncated cone shape on the lower portionof the internal storage volume 3, and forming a helicoidal annulartransverse base 4 of internal diameter "d" and external diameter "d+2e".

This cylindrical wall 2 also comprises two distal indentations 5, 6arranged symetrically to each other with respect to the longitudinalaxis of the dental implant each forming a cutting front edge at theannular transverse base 4.

In addition, in order to arrange these cutting front edges, each of theindentations 5, 6 forms a cutting face 5a, 6a inclined at an angle α ofthe order of 4 to 10 degrees with respect to the longitudinal axis ofthe implant whereas the annular transverse base 4 exhibits, between eachof the indentations, a helicoidal shape forming for each of said frontcutting faces 7, 8 a relief face 4a, 4b inclined at an angle β of theorder of 4 to 10 degrees with respect to a transverse plane.

Furthermore, the annular transverse base 4 is skewed so as to beinclined transversally in the direction of the internal storage volume 3at an angle δ of the order of 4 to 10 degrees with respect to a radialaxis.

In addition apertures such as 9, 10 of secondary wedging are drilledinto the cylindrical wall 2 and arranged in pairs symmetrically oppositeone another with respect to the longitudinal axis of the dental implant,and the axis of symmetry of which is non-intersecting with saidlongitudinal axis so that each of said apertures exhibits asupplementary cutting edge.

These apertures 9, 10, the even number of which is a function of thelength of the dental implant are distributed pairwise over that lengthof the distal section 1 situated above the indentations 5,6 and arearranged such that each pair of apertures 5,6 is displaced by 90 degreeswith respect to the neighboring pair.

In addition, the axis of each of these apertures 9, 10 is inclined in adirection opposite to the annular base 4, so as to cause the boneshavings to enter naturally into the internal storage volume 3.

The cylindrical wall 2 is moreover equipped with an external thread 11,the distal end of which starts above the indentations 5,6 which, withincreasing height, have a cross-section progressing from a trapezoidalshape for the first threads 11a and a triangular shape for the lastthreads 11b.

In addition, these threads 11a, 11b are spaced so as to define grooves12 of trapezoidal cross-section in proportion with the step and theheight of the thread.

The peripheral wall 2 comprises, finally, two indentation notches 13, 14of rectangular cross-section in the example, arranged longitudinally inthe prolongation of each of the indentations 5, 6 and each designed toexhibit a longitudinal cutting edge which makes it possible to initiatethe self-screw-threading action of the external threading 11.

These indentation notches 13, 14 extend in addition over the portion oflength of the distal section 1 provided with an external thread 11 of"truncated" section destined to accomplish the self-screw-threading.

The dental implant shown in FIGS. 1 to 4 also comprises a proximalsection 15 of widened truncated cone shape, pierced by an axial mold 16of less deep than said proximal section such that the bottom of saidmold is separated from the internal storage volume 3 by a thickness ofmaterial 17.

This mold 16 has the shape of a star, for example of the type of moldknown by the designation "TORQ", inscribed in a circle and whose areasof material forming the branches and defined by the circumscribingcircle are screw threaded.

In this manner, this mold 16 has a shape adapted to cooperate with astar-shaped tool coupled for the purpose of inserting the implant, andforms an upper threaded aperture capable of making possible theinsertion of a stump.

As regards the dental implant shown in FIGS. 5 to 7, it consists of adistal structural section identical with that of the implant describedabove (for the purposes of simplification the same reference numberswill be used to designate similar elements of the two variants of theimplant).

This dental implant hence consists principally of: a cylindrical wall 2defining an internal storage volume 3, the distal end of which has twoindentations 5,6, and forms a helicoidal annular base 4 fitted with twocutting front edges such as 8 at said indentations, apertures ofsecondary wedging 9, 10 (8 in the example given), an external threading11 and two indentation notches 13, 14.

This dental implant also comprises a proximal section 15 in the shape ofa flared truncated cone. On the other hand, instead of the mold 16, thisproximal section 15 comprises, like some current implants, a threadedaxial bore 18 destined for the insertion of a stump, and ahexagonal-shaped head 19.

As an example, the dimensions of the dental implant such as thatdescribed above may be the following, given as an indication:

total length of the order of 17 mm,

length of the distal section 1 about 13 mm,

internal diameter "d" of the annular base 4: 2.6 mm,

external diameter "d+2e" of the annular base: 3.4 mm

external diameter of the thread 11: 4 mm

maximal external diameter of the proximal section 15: 4.1 mm.

As shown in FIGS. 8, 9, the drill 20 designed to form the implantpre-cavity for the insertion of a dental implant conforming to theinvention is a helicoidal drill comprising two helicoidal grooves, andconsisting of a distal section 21 of diameter included between "d" and"d+2e", a proximal section 22 of diameter "d+2e", and an upper truncatedcone-shaped section 23 conjugated with the proximal head 15 of theimplants, prolonged in a standard manner by a handle 24 for attachmentto a tool.

As an example, for a dental implant whose dimensions correspond to thosementioned above, such a drill will have a distal section 21 of 2.8 mmdiameter and a proximal section 22 of 3.4 mm diameter.

FIG. 10 represents the implant pre-cavity 25 obtained by means of such adrill as 20, after a possible preliminary carrying out of a pre-drillingfor example by means of a drill of 2 mm diameter, comprising an upperwidening 25a, an upper bore 25b of 3.4 mm diameter in the cortical partof the bone, and in the extension of this latter a smaller bore 25c of2.8 mm diameter.

During the insertion of the implant and as shown in FIGS. 10b to 10d,this latter has a boring action of the smaller bore 25c, performed as aresult of the presence of the cutting front edges 7,8, and during whichthe osseous tissue removed is stored within the internal volume 3.

Furthermore, this implant has a self-threading action initiated by thelongitudinal cutting edge of the indentation notches 13, 14 and carriedout by the external threading 11.

Moreover, once inserted, the proximal section 15 of the implant isaccommodated in the wide opening 25a in intimate contact with the bone.

The design of this implant, with the construction of an internal storagevolume 3 adapted to accommodate the osseous tissue removed and whosedimensions for this purpose may be easily defined (by taking intoaccount, if need be, the storage volume of the apertures of secondarywedging 9, 10 and of the indentation notches 13, 14), makes it possibleto obtain both optimal intimate contact with the bone and primarystability without causing compression of the osseous tissue removed.

I claim:
 1. Surgical equipment for dental implantology comprising adrilling instrument and an endosseous dental implant, wherein:theendosseous dental implant consists of:a proximal section (15) comprisingmeans for attachment (16; 19) to a placement tool for said implant and athreaded upper aperture (16; 18) for the insertion of a stump, a tubulardistal section (1) comprising a cylindrical wall (2) defining aninternal storage volume (3) for osseous tissue and having a distal endof thickness "e" forming an annular transverse base (4) of internaldiameter "d" and external diameter "d+2e", said cylindrical wallcomprising at least one distal indentation (5, 6) forming a cuttingfront edge (7, 8) at the annular base (4), defined by said annular baseand a face (5a, 6a) of said indentation shaped so as to define a reliefface (4a, 4b) and a cutting face (5a, 6a), an external thread (11)comprising at least one distal cutting edge (13, 14) arranged on saiddental implant and starting at a distance from the annular base (4) ofthe distal section (1), the drilling instrument consists of a steppeddrill (20) possessing a distal section (21) of diameter included between"d" and "d+2e" and a proximal section (22) of diameter at least equal to"d+2e" and less than an external thread diameter (11) of the dentalimplant.
 2. Surgical equipment according to claim 1, wherein:theproximal section (15) of the dental implant comprises a truncatedconical widened upper end portion, the stepped drill (20) comprises atruncated conical upper section (23), forming an extension of theproximal section (22) and coaxial with said widened upper end portion.3. Endosseous dental implant, which comprises:a proximal section (15)comprising means for attachment (16; 19) to a placement tool for saidimplant, and a threaded upper aperture (16; 18) for the insertion of astump, a tubular distal section (1) comprising a cylindrical wall (2)defining an internal storage volume (3) for osseous tissue and having adistal end of thickness "e" forming an annular transverse base (4) ofinternal diameter "d" and external diameter "d+2e", said cylindricalwall comprising at least one distal indentation (5, 6) forming a cuttingfront edge (7, 8) at the annular base (4), defined by said annular baseand one of the shaped faces (5a, 6a) of said indentation shaped so as todefine a relief face (4a, 4b) and a cutting face (5a, 6a), an externalthread (11) comprising at least one distal cutting edge (13, 14)arranged on said dental implant and starting at a distance from theannular base (4) of the distal section (1).
 4. Dental implant accordingto claim 3, which further comprises a truncated cone-shaped upper endportion (15).
 5. Dental implant according to claim 3, wherein thecylindrical wall (2) of the distal section (1) possesses a skewed distalend forming an annular base (4) transversally inclined in the directionof the internal volume (3) defined by said peripheral wall.
 6. Dentalimplant according to claim 3, wherein the internal storage volume (3)possesses starting from the annular base (4), a truncated cone-shapedvolume portion (2a) widening in the direction of said annular base. 7.Dental implant according to claim 3, wherein the cylindrical wall (2) ofthe distal section (1) comprises two indentations (5, 6) arrangedsymmetrically to each other with respect to a longitudinal axis of saiddental implant, the annular base (4) between each of said indentationshaving a helicoidal shape forming a relief face (4a, 4b) for eachcutting front edge (7, 8).
 8. Dental implant according to claim 3,wherein the cylindrical wall (2) of the distal section (1) comprises atleast one longitudinal indentation notch (13, 14) arranged on a externalface of said wall, of transverse section adapted to form a longitudinalcutting edge.
 9. Dental implant according to claim 8, wherein eachindentation notch (13, 14) extends from the annular base (4) of thecylindrical wall (2) and is displaced at an angle to each indentation(5, 6).
 10. Dental implant according to claim 8, wherein eachindentation notch (13, 14) extends in prolongation of an indentation (5,6).
 11. Dental implant according to claim 3, wherein the external thread(11) possesses from its distal end initial threads (11a) of trapezoidalcross-section extended by threads (11b) of triangular cross-section,forming a screw thread of progressive cross-section.
 12. Dental implantaccording to claim 11, wherein the threads (11a, 11b) of the externalthreading (11) are spaced so as to define grooves (12) of trapezoidalcross-section.
 13. Dental implant according to claim 3, wherein thecylindrical wall (2) of the distal section (1) comprises circularsecondary wedging apertures (9, 10) having an axis which isnon-intersecting with respect to an axis of rotation of said implant.14. Dental implant according to claim 13, wherein an axis of eachsecondary wedging aperture (9, 10) is inclined in the direction of aproximal section (15) of said dental implant.
 15. Dental implantaccording to claims 3, in which an attachment element of the proximalsection (15) consists of a head (19) of polygonal cross-section.